Having spent ages and a small fortune sealing and painting the concrete floor in my parents garage years ago, only to find it easily chip and peel off etc I wanted a permanent finish that doesn't require any maintenance.

Power floating until 1am isn't an option as I think the neighbours might have something to say about that! Unless I can pour the concrete in at say 5pm and then finish it first thing in the morning (would take a while to go off this time of year anyway!)

Some of the Sika products mentioned above seem quite good, e.g.
Sikafloor CureHard - Transparent surface hardener, dustproofer, sealing and curing compound for concrete.

If I did go down the painted route which is the best to go for?

Carpet is a no go as it is a detached garage so will be cold and therefore damp in winter (especially with the huge pit I built!)